Seevam P.,BP Exploration and Production |
Race J.,Newcastle University |
Downie M.,Newcastle University |
Barnett J.,UK National Grid Corporation |
Cooper R.,UK National Grid Corporation
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2010
Climate change has been attributed to green house gases, with carbon dioxide (CO2) being the main contributor. Sixty to seventy percent of carbon dioxide emissions originate from fossil fuel power plants. Power companies in the UK, along with oil and gas field operators, are proposing to capture this anthropogenic CO2 and either store it in depleted reservoirs or saline aquifers (carbon capture and storage, CCS), or use it for 'Enhanced Oil Recovery' (EOR) in depleting oil and gas fields. This would involve extensive onshore and offshore pipeline systems. The decline of oil and gas production of reservoirs beyond economic feasibility will require the decommissioning onshore and offshore facilities post-production. This creates a possible opportunity for using existing pipeline infrastructure. Conversions of pipelines from natural gas service to CO2 service for EOR have been done in the United States. However, the differing sources of CO2 and the differing requirements for EOR and CCS play a significant part in allowing the re-use of existing infrastructure. The effect of compositions, the phase of transportation, the original pipeline specifications, and also the pipeline route require major studies prior to allowing re-use. This paper will first review the requirements for specifying the purity of the CO2 for CCS and to highlight the implications that the presence of impurities and the current water specifications for pipelines has on the phase diagram and the associated physical properties of the CO2 stream. A 'best' and 'worst' case impurity specification will be identified. Then an analysis on the impact and subsequent validation, of equations of state based on available experimental data on the phase modelling of anthropogenic CO2 is presented. A case study involving an existing 300km gas pipeline in the National Transmission System (NTS) in the UK is then modelled, to demonstrate the feasibility of using this pipeline to transport anthropogenic CO2. The various issues involved for the selected 'best' and 'worst' case specification are also covered. This is then followed by an investigation of the options for transport in the 'gas' phase and 'supercritical' phases, and also identifying the limitations on re-using pipeline infrastructure for CCS. Copyright © 2010 by ASME.
Harwood J.,Northumbria University |
Aplin A.C.,Northumbria University |
Aplin A.C.,Durham University |
Fialips C.I.,Northumbria University |
And 5 more authors.
Journal of Sedimentary Research | Year: 2013
Evaluating the timing and origin of quartz cement is central to understanding how porosity is lost in sandstones during burial. Kinetic models of quartz cementation have been calibrated using large-scale datasets but have never been tested at the microscopic level at which cement forms. Here, we use high-precision, in situ oxygen isotope analyses on sandstone from the Jurassic Ness Formation from the North Sea to reveal the growth history of single quartz overgrowths to a resolution of 2 μm. Measured δ18O (cement) range from +28 to +20% V-SMOW in early to late cement and are consistent with quartz cementation models that propose the bulk of quartz precipitates as a continuous process beginning at 60-70 °C. Quantitative X-ray Diffraction analyses and clay mineralogical analysis of interbedded shales are inconsistent with a silica source from shale, implying that silica for the cement is sourced internally to the sand. These isotope data are broadly consistent with predictive, conceptual quartz cementation models and provide a critical link from micron-scale measurements to basin-scale predictions and observations. Copyright © 2013, SEPM (Society for Sedimentary Geology).
Go J.,Imperial College London |
Bortone I.,Imperial College London |
Muggeridge A.,Imperial College London |
Smalley C.,BP Exploration and Production
Transport in Porous Media | Year: 2014
Sudden changes in isotopic tracer concentration in pore waters have been interpreted as indicating barriers to vertical advective flow through porous rocks in the subsurface, e.g. step changes in 87Sr/86Sr ratio are often used in the oil and gas industry as a signature of reservoir compartmentalisation. This study shows that this is not necessarily the case. It can take millions of years for such step changes to equilibrate by diffusion if there is no flow resulting from pressure or density gradients even in high permeability, high porosity rocks, particularly if the water saturation is low. Changes in tracer concentration gradients can be good indicators of changes in porosity (or water saturation) between layers. In contrast changes in sorption without a change in porosity are almost impossible to identify. The time taken for concentration gradients to equilibrate is affected by the layer properties but can be quickly estimated from the harmonic average of the effective diffusion coefficient for each layer and a simple analytical expression for a homogeneous system. This was achieved by performing a sensitivity analysis on different layer properties (porosity contrast, saturation contrast, sorption contrast, thickness ratio) using existing analytical solutions for diffusion in layered systems. © 2014, Springer Science+Business Media Dordrecht.
Dale A.,Imperial College London |
John C.M.,Imperial College London |
Mozley P.S.,New Mexico Institute of Mining and Technology |
Smalley P. C.,BP Exploration and Production |
Muggeridge A.H.,Imperial College London
Earth and Planetary Science Letters | Year: 2014
Septarian carbonate concretions contain carbonate precipitated during progressive growth of the concretion and subsequent fracture-filling. As such, they have been used to track variations in δ13C and δ18O of pore waters during diagenesis and to define diagenetic zones in clastic rocks. However, the δ18O value of the carbonate is dependent on precipitation temperature and the δ18O value of the pore fluid from which it precipitated. Interpretations must assume one of these parameters, both of which are highly variable through time in diagenetic settings. Carbonate clumped isotopes of the cement can provide independent estimates of temperature of precipitation, allowing the pore-water δ18O to be back-calculated. Here, we use this technique on carbonate concretions and fracture fills of the Upper Cretaceous Prairie Canyon Member, Mancos Shale, Colorado. We sampled concretions from two permeable horizons separated by a 5 m shale layer, with one permeable horizon containing concretions with septarian fractures. We show cores precipitated at cooler temperatures (31 °C, ~660 m burial depth) than the rims (68 °C (~1980 m burial depth) and relate that to the δ13Ccarbonate values to suggest the concretion core precipitated in the methanogenic zone, with increasing input from thermogenically produced CO2. The two concretion-bearing horizons have different back-calculated δ18Oporewater values (mean -2.65‰ and 1.13‰ VSMOW) for cements formed at the same temperature and similar δ13C values, suggesting the shale layer present between the two horizons acted as a barrier to fluid mixing. Additionally, the δ18Ocarbonate of the septarian fractures (-13.8‰ VPBD) are due to precipitation at high temperatures (102 to 115 °C) from a fluid with a mean δ18Oporewater of 0.32‰ (VSMOW). Therefore, we can tie in the cementation history of the formation to temporal and spatial variations in δ18Oporewater. © 2014 The Authors.
Smedley P.,BP Exploration and Production |
O'Connor P.,BP Exploration and Production
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2011
The ISO 19900 series of Standards address the design, construction, transportation, installation, integrity management and assessment of offshore structures. Offshore structural types covered by ISO include: bottom-founded 'fixed' steel structures; fixed concrete structures; floating structures such as monohull FPSOs, semi-submersibles and spar platforms; arctic structures; and site-specific assessment of jack-up platforms. All the fundamental ISO Offshore Structural Standards have now been published representing a major achievement for the Oil and Gas Industry and representative National Standards Organizations. A summary of the background to achieving this milestone is presented in this paper. In parallel, other Codes and Standards bodies such as API, CEN, CSA, Norsok and the Classification Societies are looking to harmonize some, or all, of their Offshore Structures Standards in-line with ISO, wherever this is desirable and practical. API, in particular, have been pro-active in reviewing and revising their Offshore Recommended Practices (RPs) to maximize consistency with ISO, including revising the scope and content of a number of existing API RPs, adopting ISO language, and embracing technical content. Given API's long heritage of Offshore Standards it is not surprising that this remains very much a mutual effort between ISO and API with much in ISO Standards building on existing API design practice. Now published, those involved in developing and maintaining the ISO 19900 series of Standards have to deal with both new and existing challenges, including encouraging wider awareness and adoption of these Standards, enhancing the harmonization effort, ensuring technical advances are captured in timely revisions to these Standards, and most pressing to ensure that the next generation of offshore engineers are encouraged to participate in the long-term development of the Standards that they will be using and questioning. This paper is one of a series of papers at this OMAE Conference that outline the technical content and future strategy of the ISO Offshore Structures Standards. Copyright © 2011 by ASME.